io6 THE INTEGUMENTAL SKELETON OF THE IMAGO. 



Sometimes there is a distinct movable articulation between 

 the apodeme and the plate on which it acts. Such apodemes 

 were distinguished by Audouin as epidemes ; both terms are 

 useful, 



Endopophyses, Entosterna, and Diaphragmata are terms applied 

 to the internal inflections of the skeleton. They are plates of 

 chitin, which form partial septa dividing the body cavity, either 

 giving attachment to the muscles, strength to the skeleton, 

 or support to some of the internal organs. The diaphragmata 

 are transverse septa ; the entosterna are consolidated median 

 sutures in the ventral region. Endopophysis is a general term 

 for any internal inflection which has not received a distinctive 

 appellation. 



2. THE HEAD CAPSULE. 



(a) General Morphology. 



The head capsule of an insect may be said to be a subovoid 

 capsule with an anterior opening, the mouth ; and a posterior 

 opening, the occipital foramen, with the edges of which the 

 skin of the neck is continuous. It is usually described as con- 

 sisting of an epicranium, which forms the convex upper surface 

 and sides of the head capsule, of a plate on its under surface, 



Bibliography : — 



42. Leydig, F., ' Vom Bau des thierischen Korpers,' Tubingen, 8vo, heft i., 



1864. 



43. Balfour, 'Comparative Embryology,' Lond., 1881. 



44. Rolleston'S ' Forms of Animal Life,' 2nd edit. Revised and 

 enlarged by W. Hatchett Jackson. 8vo, Oxford, 1888. 



Beside the works on insect Anatomy and Development already quoted, 

 the reader who desires to attain further information on the most recent 

 morphological speculations should consult : 



45. Gaskell, W. H., ' On the Origin of the Central Nervous System of 

 Vertebrates,' ' Brain,' vol. xii., pt. i, 1879. 



46. Bellonci, 'Sur la Structure et les Supports des Lobes Olfactifs dans 

 les Arthropods Superieurs et les Vertebras.' Archiv. Ital. de Biologie, 

 torn, iii., p. 191. 



47. Gaskell, W. H., 'On the Origin of Vertebrates from a Crustacean- 

 like Ancestor.' Quart. Jour. Mic. Sc, vol. xxxi., pt. 3, 1890. 



48. Patten, W., ' On the Origin of Vertebrates from Arachnids.' Quart. 

 Journ. Mic. Sc, vol. xxxi., pt. 3, 1890. 



